Solvent bleaching

ABSTRACT

FABRICS WITH BOTH OLEPHILIC AND HYDROPHILIC CHARACTERISTICS ARE CLEANSED WITH COMPOSITIONS OF ORGANIC CLEANSING SOLVENT THROUGHOUT WHICH AN AQUEOUS BLEACHING PHASE IS DISPERSED. BLEACHING AGENT REMAINING IN THE FABRIC IS REMOVED BY A RINSE SOLUTION CONTAINING THE COMBINATION OF AN ALCOHOL OR LIKE WATER SOLUBLE COMPONENT AND THE CLEANSING SOLVENT.

United States Patent O 3,679,590 SOLVENT BLEACHING Charles L. Cormany,Wadsworth, and John A. Spotts, Jr., Akron, Ohio, assignors to PPGIndustries, Inc., Pittsburgh, Pa. No Drawing. Filed Sept. 11, 1969, Ser.No. 857,214 Int. Cl. 0116 7/54 US. Cl. 252-104 11 Claims ABSTRACT OF THEDISCLOSURE Fabrics with both oleophilic and hydrophilic characteristicsare cleansed with compositions of organic cleansing solvent throughoutwhich an aqueous bleaching phase is dispersed. Bleaching agent remainingin the fabric is removed by a rinse solution containing the combinationof an alcohol or like water soluble component and the cleansing solvent.

BACKGROUND OF THE INVENTION The development and increased use ofcotton-polyester fabrics and the permanent press finishing of fabrics ofcotton and cotton-polyester blend fabrics have created new launderingproblems. These fabrics and finishes have hydrophobic tendencies.Consequently, they tend to repel water or otherwise be resistant tocleansing with conventional aqueous bleaching systems. On the otherhand, traditional dry cleaning techniques, while effective with respectto oleophilic soils and stains are of little value -in coping withhydrophilic stains.

Permanent press white garments such as mens shirts quite commonlyencounter oleophilic soils (oils greases, etc.) and hydrophilic soils orstains such as mustard, catsup, coffee and grape juice stains. Effectivelaundering must handle both categories. However, present day drycleaning is only capable of coping with the olephilic soils, beingineffective with respect to the hydrophilic soils. Conversely, aqueousbleaching systems designed to cope with hydrophilic stains on cotton andother hydrophilic fabrics such as linen, leave untouched oleophilicsoils. 'Ihus, neither of the two general cleaning expedients practicedby commercial laundries alone are completely satisfactory.

THE INVENTION This invention provides for eltectively coping with botholeophilic and hydrophilic soils simultaneously and thus provides for aunitary cleansing treatment. It further provides an overall process forlaundering fabrics of cotton-polyester blends and on the permanent presstype which is economical and capable of being practiced in equipmentappropriate for use in the commercial laundry.

According to this invention, a laundering or cleaning bath is providedwhich is capable of treating fabrics soiled with both oleophilic andhydrophilic stains or soils by single contact therewith. This isaccomplished in accordance with the present invention by the provisionof a cleaning bath which has as primary cleansing components both anorganic, substantially water immiscible cleaning solvent and an aqueousphase containing a water soluble bleach. Laundering baths hereincontemplated thus contain as a principal component methylchloroform,perchloroethylene, or like halogenated organic cleaning solvent alongwith an aqueous solution "ice of a water soluble bleaching agent such asaqueous hydrogen peroxide or a water soluble hypochlorite such as sodiumhypochlorite. These bleaching agents are substantially insoluble in theorganic cleaning solvent of the bath.

For this combination of substantially water immiscible organic cleaningsolvent and aqueous solution of an organic insoluble water solublebleaching agent to be effective, it is important these two principalcomponents be inter-related to one another in a particular fashion. Ithas been discovered it is important the laundering bath include adistinct aqueous phase which constitutes a minor proportion of the bath,typically upwards of 0.1 up to 5 (rarely more than 10) percent by weightof the baths organic cleaning solvent constituent. A distinct aqueousphase must be present contrasted with water or aqueous solution whichmay be dissolved in the organic cleaning solvent (even the substantiallywater immiscible solvents may dissolve some water).

For desirable results to accrue, the aqueous phase is dispersedthroughout the organic cleaning solution phase of the bath. Distributionof the aqueous phase as a discontinuous phase through the continuousphase of organic cleaning solvent component of the bath not only insuresthere be proper contact between the goods and aqueous bleachingcomponent, but prevents spot bleaching and non-uniform stain removal. Aswill hereinafter be further discussed, there are various sources of thewater for this aqueous phase. Thus, for example, a portion of the watercomprisnig the dispersed aqueous phase can be provided by water broughtinto the bath along with the materials undergoing the treatment.Without, however, a pretreating step to control the fabrics watercontent prior to contact with the cleansing bath of organic cleaningsolvent, there is a degree of uncertainty. For this reason, recommendedpractices insure the presence of at least the minimum effective watercontent dispersed in the organic cleaning solvent of the treating bathwhether or not water is introduced along with the materials subjected tothe cleansing treatment.

Regardless of the source of all the water present in the cleansingcomposition, the water content of the bath constitutes but a minorportion of the total treating bath. This small water phase isdistributed in the bath so that it contacts uniformly the material beingcleansed. Small droplets of aqueous bleaching agent are thus dis persedin the continuous organic phase of the bath. Distribution of aqueoushydrogen peroxide throughout a substantially water immiscible cleaningsolvent such as methylchloroform is accomplished, according to oneembodiment, by use of suspending agent such as a long chain alkyl sodiumphosphate. Suspending agents or surfactants facilitate dispersion of theaqueous hydrogen peroxide phase as small droplets uniformly throughoutthe methylchloroform even though the aqueous phase constitutes but aminor weight portion, for example, from 0.5 to 3 weight percent, of themethylchloroform.

With the aqueous hydrogen peroxide phase dispersed in the form of finewater immiscible particles, e.g., globules from 1 to 500 microns,throughout the methylchloroform, the bath performs bleaching as if itwas solely constituted of aqueous hydrogen peroxide, yet those fabricstreated with special advantage by the present invention (i.e., thosewith oleophilic and hydrophilic properties) are not degraded. By virtueof the present invention, polyester-containing fabric and permanentpress treated fabrics may be cleansed of both oleophilic and hydrophilicsoils without significant fiber degradation.

Among other things, these ends are accomplished by restricting thecontact between material and aqueous hydrogen peroxide and controllingor directing the hydrogen peroxide bleaching action. To limit the extentof the bleaching action, contact time between the peroxide and materialshould be controlled. Prolonged treatment, for example, on the order ofseveral hours is definitely deleterious to fabric strength and is alsoexpensive. Thus, eflective contact between fabric and bleaching agent,pursuant'to this invention is on the order of several minutes to lessthan an hour, notably from to 30 minutes. As will hereinafter bediscussed in more detail, restricting contact times is best accomplishedby use of special expedients.

A further advantage of dispersing a relatively small aqueous bleachingphase in an organic water immisible cleaning solvent is that the totalamount of hydrogen peroxide or like aqueous bleaching agent required toeffect the desirable level of strain removal and brightening is wellbelow that which would be necessary in a treating bath without theorganic treating solvent. In this aspect, the organic solvent acts as adistributing agent. Although diluting the bleaching agents concentrationin the bath, it does not reduce its bleaching action to a levelcomparable to single phase aqueous bleach bath with the same totalamount of bleach agent.

The following examples illustrate the manner in which the presentinvention may be practiced:

EXAMPLE 1 A solution was prepared by passing 3600 milliliters ofmethylchloroform containing 29.9 grams (0.5 weight percent ofmethylchloroform) of Alkapent 6TD (a long chain alkyl dihydrogenphosphate sold by the Weyland Chemical Division of Philip A. HuntChemical Corporation) and 47.8 milliliters (1.0 percent by weight of themethylchloroform) of distilled water through 50 cubic centimeters ofsodium carbonate disposed in a glass column one inch in diameter. Thetreatment with soda ash converted the Alkapent 6TD (a long chain alkyldihydrogen phosphate) to long chain alkyl sodium phosphates.

From this solution a series of 150 milliliter bleach baths wereprovided. Ten gram scoured cotton panels were placed in the solution fortwo minutes, then removed. Thereafter, the specified amount of hydrogenperoxide (as 70 percent hydrogen peroxide) was rapidly added and thesolution mixed. A cleaning solution thus resulted in which an immiscibleaqueous hydrogen peroxide phase was dispersed in the methylchloroform.The panels were returned to the bath at room temperature (about 25 C.)for 10 minutes, and then removed, rinsed thoroughly with distilled waterthen acetone following which they were air dried. The panels were ironedand their blue reflectance values measured. Also, the fluidity values ofthe treated cloth was determined by the American Association of TextileChemists and Colorists stand- 4 EXAMPLE 2 TABLE 2 Weight percent 1 ofBlue reflectance, 70% H 0 used: percent 1.3 70.2

1 By weight of the cotton panel.

Contact between the fabric and the cleaning solution is relativelybrief; contact for as little as about 5 minutes to 30 or 40 minutesachieve a high degree of bleaching. This is illustrated by the followingexamples:

EXAMPLE 3 A stock solution was prepared by passing three liters ofmethylchloroform containing 20 grams of Alkapent 6TD (0.5 percent byWeight of the methylchloroform) and 40 milliliters of distilled waterthrough a bed of sodium carbonate. The sodium carbonate treatmentconverted the Alkapent 6TD (long chain alkyl dihydrogen phosphate) to along chain alkyl sodium and disodium phosphate. Ten grams scoured cottonpanels were then placed for the specified period of time in milliliterportions of the bleach liquor to which the amounts of 70 percenthydrogen peroxide specified in Table 3 had been added and then removed,water Washed, air dried and ironed. The reflectance and fluidity of manyof these samples were determined and are reported in Table 3. Withoutthe treatment, the cotton had a blue reflectance of 64.7 percent and aCuam fluidity of 2.2 rhes.

TAB LE 3 Concentration of Blue 70% E201 reflec- Cuam (OW G) tanee,fluidity percent percent (rhes) Time (minutes):

meweeeeweeeeeerowwwuee 'coaccouzoqoocawqvhmwc 1 OWG=On the weight of thegoods.

EXAMPLE 4 The procedure of Example 3 was repeated with three differentlevels of hydrogen peroxide. The cotton without bleaching had a BlueReflectance of 65.7 percent and a Cuam fluidity of 2.2 rhes.

5 The following Table 4 lists the data:

TAB LE 4 Concentration of Blue 70% H202 reflec- Guam (W G) tance,fluidity percent percent (rhes) Time (minutes):

1 OWG=0n the weight of the goods.

EXAMPLE 5 A stock solution of bleach bath compositions for the firstfour runs reported in Table 5 was prepared by adding 0.17 gram of sodiumcarbonate in water ot 150 milliliters of methylchloroform compositionwhich contained 0.5 weight percent of Alkapent 6TD, the amount of waterused to dissolve the sodium carbonate being 0.5, 1.0, 1.5 and 2.0milliliters respectively. The remaining three runs used a stock solutionprovided by adding 1.8 grams of sodium carbonate dissolved in 5milliliters of water to 750 milliliters of methylchloroforrn containing0.5 weight percent Alkapent 6TD. Additionally, 1.0 milliliter and 2.0milliliters of water were added respectively to the last two samples. Aquantity of 70 percent hydrogen peroxide (0.78 milliliter) was added toeach 150 milliliter portion. The ten-gram scoured cotton panels werethen in the solvent for 10 minutes, the panels removed, rinsed withdistilled water, air dried and ironed.

NHHHOQ 1 Exclusive 0! water added as 70% 1120;. I OWG=By weight of thecotton goods. 8 0WS=By weight of the methylchloroform.

As noted, the cleansing solution includes a suspending agent whichserves to facilitate and maintain the aqueous bleaching phase in thedesirable dispersed state. In many instances, besides performing thisimportant function, these agents facilitate the bleaching action of theagent. Many are also detergents (as well as suspending agents) and hencetheir presence adds this to the cleansing capacity of the treatingsolution. Most are either anionic or nonionic.

Any one of many suspending agents work as evidenced by the examples. Inaddition, these may be mentioned: octyl phenoxy polyethoxy ethanol(nonionic), polyethylene glycol ester of oleic acid (nonionic), nonylphenyl polyethylene glycol ether (nonionic), nonyl phenoxy poly(ethyleneoxy) ethanol (nonionic) polyoxyethylene polyol fatty acidesters (nonionic), sodium dodecyl diphenyl ether disulfonate (anionic),octyl phenoxy polyethoxy ethanol (nonionic), alkylaryl polyether alcohol(nonionic), octyl phenoxy ethanol (nonionic) and octyl phenoxy diethoxyethanol (nonionic).

An important consideration is timely and complete removal of activebleaching agent, notably active hydrogen peroxide from the treatedfabric. Fabrics of the type most appropriately treated by this inventionlose strength if they retain hydrogen peroxide (or like bleachingagent). Overcontact with bleaching agent is detrimental to fabricstrength. It has been found that even such minor amounts of residualbleaching agent which remain in the fabric can cause serious fabricdegradation. Detrimental amounts of hydrogen peroxide and the like areretained by the fabric even after the fabric is withdrawn from thetreating bath and solvent rinsed by normal expedients.

According to an embodiment of this invention, a particularly effectivemeans for removing residual hydrogen peroxide and thereby preventingfiber degradation has been developed. Various attempts to use componentsof the cleaning bath for removal of hydrogen peroxide did not proveeffective as illustrated by Example 6.

EXAMPLE 6 Ten gram scoured cotton panels were treated for 10 minutes atroom temperature in a cleansing bath provided by passing 150 millilitersof methylchloroform containing one gram of Alkapent 6TD and two grams ofdistilled water through a sodium carbonate column to which was added2.34 milliliters of 70 percent hydrogen peroxide. Thereafter, the panelswere rinsed as described in Table 6 and the Blue Reflectance andfluidity of the panels measured:

TABLE 6 Blue reflec- Guam tance, fluidity Bun Type of rinse treatmentpercent (rhes) (1) Water M 79.4 8.0 (2) Three consecutive rinses withmethyl- 79. 9 15.4

chloroform. (3) Sameas (2) but with 0.5% alkaline Alka- 80. 8 17. 6

pent 6TD and 1.0% H202. (4) Rinse once with the composition of (3) 80. 110.3

followed by rinse (2). (5) Same as (4) except that the 0.05% formic 80.9 18. 4

acid included in the composition of (3). (6) Rinsed twice withmethylchlorororm 79. 5 12.4

containing acidic Alkapent 6TD followed by two rinses ofmethylchloroorm.

In each of these runs, fiber degradation progressed further thandesirable, as evidenced by the high Cuam fluidity values.

Residual hydrogen peroxide or like bleaching agent, it has beendiscovered, is reduced to a tolerably low level (i.e., to a level atwhich serious fiber degradation is avoided) in the treated fabric byrinsing the fabric with a special formulation containing as basicconstituents an organic cleaning solvent, ideally the same organicsolvent employed in the cleaning step, along with a minor concentrationof a substantially water soluble alcohol. Such alcohols includemonohydric aliphatic alcohols such as ethanol, isopropanol, n-propanol,t-butanol, isobutanol, the amyl alcohols such as t-amyl alcohol, and thelike, notably, alkanols containing from 2 to 5 carbon atoms. Usefulalcohol concentrations in the rinse compositions are from 1 to 10percent or even 15 percent by volume of the organic cleansing solvent.Preferably, monohydric alcohols should have a substantial miscibility inboth the organic cleaning solvent and in water, so that in theconcentrations it is present it will not form (or cause to form) a.second distinct liquid phase. It is desirable that the rinse compositionbefore and after use be as a single liquid phase. Alcohols with arelatively low boiling point (below about C.) are advantageous; they arereadily removed from the fabric by those drying procedures normallyutilized in connection with the cleaning of fabrics in commerciallaundry operations.

Where the concentration of the alcohol creates fire hazards or otherdisadvantages, a monoether of a dihydric compound, notably, lower alkylmonoethers of glycols such as methyl Cellosolve, ethyl ether or glycol,and like water soluble, organic soluble monoether can be included in therinse formulation. This permits a reduction in the alkanol withouthampering the compositions performance.

Other materials useful in lieu of or in addition to the alcohols andethers already described include dioxane, ketones such as acetone andmethyl ethyl ketone, etc.

Rinse compositions will also contain a small amount of water. For onething, residual water from the treated fabric will find its way into therinse. As hereinafter discussed, use as by recycle is contemplated ofrinse solution which has previously been in contact with treated fabric.Water contents range from about 0.1 to weight percent, of the organicsolvent, or sometimes even higher (e.g., up to about percent). It ispreferred practice for the Water content to be below that which willgive rise to a separate (immiscible aqueous) phase; ergo, the water ispresent as dissolved water. A separate liquid phase of any kind presentscomplications in the adaption of more common dry cleaning equipment tothis method and hence is better avoided.

Other expedients reduce residual hydrogen peroxide in the fabric. Forexample, residual hydrogen peroxide may in effect be removed by contactwith a material with which it reacts. Various reagents which reducehydrogen peroxide are thus of use. Some such reagents include inorganicreducing agents such as ferrous ammonium sulfate, sodium sulfite, sodiumbisulfite, potassium sulfite, potassium bisulfite, ammonium sulfate,ammonium bisulfite and organic reducing agents exemplified by thioureassuch as allyl thiourea diethylthiourea and dibutylthiourea; aldehydessuch as formaldehyde, pyruvaldehyde and glycidaldehyde.

In using these reducing agents to remove bleaching agent, it isadvisable to rinse the fabric free of products (salts) of the reductionof hydrogen peroxide. Often those salts can cause discoloration or odor,even as such, or after further treatment of the fabric. Ironing or otherheating will often result in discoloration with some of the salts. Watersoluble salts, for example, may be water rinsed away. Organics can bedissolved in an appropriate organic rinse.

EXAMPLE 7 Cotton fabric was treated for 10 minutes at room temperaturein a bath of methylchloroform containing 0.5 percent Triton GR7 (a Rhome& Haas product; dioctyl sodium sulfosuccinate) anionic suspending agentand by weight of the fabric, 30 percent water, 4.5 percent ammoniumhydroxide and 10 percent of 70 percent hydrogen peroxide. After beingWithdrawn from the bleaching bath, the fabric was contacted for 9minutes with sixty weight parts per part of fabric of a liquidcomposition of methylchloroform containing 0.5 weight percent of TritonGR7 the solvent and (by weight of the fabric) 20' percent water, and 7percent sodium sulfite. Three one-minute methylchloroform rinsesfollowed. Residual hydrogen peroxide in the fabric was 0.19 percent.

The following examples illustrate rinsing techniques for reducingresidual hydrogen peroxide on fabrics which have been cleansed bytreatment with a bath of an organic cleansing solvent through which adispersed aqueous water soluble bleach containing phase is disperseduniformly.

EXAMPLE 8 In each of the tests, a ten gram neutral scoured cotton panelwas bleached for 10 minutes at room temperature in 150 milliliters ofmethylchloroform composition to which 0.5 gram of Al'kapent 6TD, 0J5milliliter of distilled water, 0.085 gram of sodium carbonate and 0.5milliliter of 70 percent hydrogen peroxide had been added. The panelswere then removed, hand squeezed, dried and rinsed with the compositionsand in the manner described in Table 7 :Following the rinsing, a 5 gramportion of the cotton panel was tested to determine its residualhydrogen peroxide content.

Unless otherwise indicated, each rinse was for two minutes, the volumeof rinse material was 250 milliliters and six rinses were employed.

TABLE 7 Quantity of H202 Rinse bath remaining Blue in fabric, refiec-Guam Volume percent tance fluidity Run No. Additive percent OWG percent'(rhes) Control- 1 2-propanol 5 2--. do 10 3 Dioxane 5 4". Quinoline 5 5Z-methyl-l- 10 2 propanoll. 10

-propano 6 {Water o. a

{Z-propanol 10 Water 2 O. 6 8 2-propanol 10 9 {2-propanol 10 Water 0.3

1 Fabric after bleaching.

7 Percent by weight of methylchloroform.

3 50/50 Dacron/cotton panels with permanent press resin finishtreatment.

1 Rinse volumes of milliliters.

EXAMPLE 9 A ten gram neutral cotton panel was treated for 10 minutes atroom temperature with 150 milliliter portions of a stock solutionprepared by adding 1.7 grams of sodium carbonate, 10 grams of Alkapent6TD and 10 milliliters of distilled water to 3,000 milliliters ofperchloroethylene and to which portion 0.5 milliliter of 70 percenthydrogen peroxide was added. After removal from the treating bath, thepanel was rinsed six times using each time 250 milliliters of aperchloroethylene rinse com position containing 10 percent by volume2-propanol and 1 milliliter of distilled water. Following this rinsing,the panel was dried in a forced air oven at about 70 C. until allsolvent vapors had been expelled, then ironed. Its residual hydrogenperoxide content was 0.09 percent and it had a Cuam fluidity of 3.8rhes.

Removal of stains by the cleansing composition of this invention isillustrated in the following examples.

EXAMPLE 10 Samples of fabric each with mustard, ball point ink, grapejuice, coffee or chocolate milk stains were prepared and then placed for20 minutes at room temperature in a bleach bath of methylchloroform towhich had been added (by weight of the methylchloroform) 6.5 percent of70 percent hydrogen peroxide, 0.85 percent sodium carbonate, 5.0 percentwater and by weight percent of the goods 0.25 percent Alkapent 6TD, theamount of such bleach bath providing a 20:1 weight ratio of solvent togoods.

The fabrics were then removed, their residual hydrogen peroxidedestroyed, and their reflectances determined with these results:

TABLE 8 Initial reflectance, percent Final reflectance, percent BlueGreen Blue Green Stain Inc. Excfl Inc. Inc. Eire. Inc.

100% COTTON FAB RIOS 37. 4 36. 9 79. 2 60. 58. 8 85. 43. 4 43. 62. 1 61.7 61. 9 74. 77. 2 77. 3 57. 7 81. 9 81. 6 84. Grape juice 27. 9 26. 645. 5 56. 9 56. 9 75. Chocolate mil 56. 7 56. 6 69. 4 66. 0 64. 3 75.

50/50 DACRON-COITON FABRICS Mustard 50. l 45. 9 77. 1 68. 4 60. 0 80. 6Coffee 43. 6 37. 9 58. 5 73. 2 65. 77. 6 Ink 84. 6 73. 7 65. 3 87. 5 76.4 79. 9 Grape iuic 39. 6 36. 4 60. 6 82. 4 72. 3 80. 4 Chocolate milk---62. 9 55. 1 69. 5 81. 5 71. 7 79. 9

1 Ine.=Including fluorescence. 1 Exc.=Excluding fluorescence.

Organic cleaning solvents other than methylchloroform, as exemplified bythe use of perchloroethylene in Example 9, are effective. Usually thesecleaning solvents are essentially water immiscible. The more notable arehalogenated hydrocarbon solvents, having 1 to 3 carbons. Besidesmethylchloroform these include chloroform, carbon tetrachloride,methylene chloride, methylene dichloride, ethylene dichloride,trichloroethylene, perchloroethylene, many of their fluorinated orchlorofluorocounterparts such as 1,1,2-trifluoro 1,2,2-trichloroethane,difluoromethane, tritluoroethylene, chloro-fiuoro hydrocarbon cleaningsolvents, such as trichlorofluoromethane, 1,1,2,2-tetrafiuoro1,2-dichloroethane, as well as other halogenated solvents containing twoor more different halogens. Other solvents include petroleum drycleaning solvents such as the Stoddards Solvents.

Example 11 illustrates applicability of halogen bearing organic cleaningsolvents.

EXAMPLE 11 The general procedure involved treating with a cleansing bathprovided by mixing about 0.5 millimeter of 70 percent hydrogen peroxideinto 150 milliliters of a solution provided by adding 0.55 gram ofAlkapent 6TD and 0.5 millimeter of 3.2 Normal sodium carbonate to theorganic solvent. A ten gram sample of 100 percent scoured cotton wasplaced in the bath at room temperature and agitated for minutes. Thebath composition and liquorto-goods ratio in the treatment was such thatthe hydrogen peroxide content of the bath was 6.4 percent, the sodiumcarbonate was 0.85 percent, the water constituted 5 percent (all byweight of the organic cleaning solvent) and the Alkapent 6TD content was0.25 percent by weight of the goods.

Following the cleansing treatment, the fabric from each cleansing stepwas then treated for 5 minutes at 25 C. in a bath of the solventemployed in the cleansing step containing sodium sulfite (Na SO a smallamount of water and about 1 gram of Triton GR-7 (an anionic neutraldetergent). The sodium sulfite reacted with residual hydrogen peroxidein the fabric.

The fabric was then placed in the bath of the solvent containing a smallamount of dilute hydrochloric acid and about 1 gram of Triton GR-7 forthe purpose of destroying any salts generated by the sulfite. Then itwas rinsed with solvent only to remove any residual Triton (BR-7following which the sample was air dried for three minutes and thenironed. Samples ironed to dryness had their reflectance valuesdetermined.

In lieu of hydrogen peroxide as the bleaching component of the cleansingor organic solvent bleaching system, other water soluble bleaches may beemployed, especially those water'soluble bleaches which aresubstantially insoluble in the organic cleaning solvent of the cleaningbath. Besides hydrogen peroxide, alkali metal peroxides such as sodiumperoxide, hypochlorous acid and the alkali hypochlorites such as sodiumhypochlorite, potassium hypochlorite and lithium hypochlorite as well asmixtures of one or more (including hydrogen peroxide) are effective.

Typical practice of the invention herein described utilizing equipmentof the type available to and in the commercial laundry involves charginga dry cleaning wheel with soiled garment following which the cleansingcomposition (of the invention) is then introduced into the wheel. Thefabric is agitated in the cleaning solvent usually for from 5 to 25minutes whereupon the solvent is drained promptly from the wheel and thegarments therein extracted (spin dried), a typical time period for thisbeing from 2 to 5 minutes.

Once the garments are freed of extraneous cleansing solvent, they arerinsed with a solution comprised of the organic cleaning solvent(utilized in the cleaning step), a minor amount of monohydric alcoholsuch as isopropyl alcohol alone or in combination with methyl-Cellosolveand a small amount of water. Effective results are obtained when therinse solution is continuously circulated through and out of the drycleaning wheel. The monohydric constituents should be present in aquantity suflicient to dissolve the hydrogen peroxide from the fabricand also avoid the formation of separate immiscible phase in thecirculating rinse solution. It especially is important to maintain therinse solutions as a single liquid phase when the circulating solutionis passed through filters (for purification) designed to handle but asingle liquid phase, a typical characteristic of filter systems in manydry cleaning apparatus.

Residual hydrogen peroxide in the garments is reduced with particulareffectiveness by continuously removing rinse solution from the wheel,destroying or reducing the peroxide content of the solution, andreturning it to the wheel. Contacting the rinse composition withmaterials which selectively decompose hydrogen peroxide will accomplishthis. Typically, polyvalent metals are of use in this connection.Palladium deposited on a particulate clay substrate, for example,provides an excellent bed through which to pass the rinse solution forthe purpose of destroying hydrogen peroxide. Other metals useful in lieuof palladium include silver, platinum, ruthenium, manganese and thelike. In general, those polyvalent metals which do not form oxidessoluble in the rinse solution are preferred since soluble oxidesdissolve and accumulate, and ultimately will have to be removed from thesystem. Ferromanganese alloys, silver oxide, activated carbon, cobaltchloride impregnated on calcium sulfate are among many other usefulmaterials.

Upon freeing the garments residual hydrogen peroxide, any residual rinsesolvent is drained from the fabrics usually in less than 5 or 10minutes. The garments are then dried by a typical procedure employed indry cleaning, notably by contact with hot air for several minutes.Solvent vapors in the hot air are usually removed by conl l densationfrom the hot air exiting the dry cleaning wheel. Other steps used in drycleaning may be performed such as deodorizing.

EXAMPLE 12 Use of a commercial type short cycle dry cleaning unit withsome adaptation in materials of construction (e.g., use of polyethylenetubing in lieu of rubber hosing) and provision of two tanks for handlingtwo different liquid compositions demonstrated the applicability of thesystem to commercal equipment as follows.

Cleansing solution was provided by adding 0.38 pound of Alkapent 6TD,29.4 grams sodium carbonate monohydrate in 199 milliliters of distilledwater and 260 milliliters of 35 percent hydrogen peroxide to 14 gallonsof methylchloroform. Eight gallons of this solution was fed to the drycleaning wheel which contained five pounds of fabric (of the typeidentified in the table). Then 260 milliliters of 35 percent hydrogenperoxide was added, whereafter the fabric and solvent were agitated inthe wheel for 20 minutes at room temperature and the liquid drained fromthe wheel in three minutes.

Rinsing was then commenced by circulating several gallons per minute ofa methylchloroform solution containing 5 volume percent (2.15 gallons)isopropanol, 2 volume percent (1.02 gallons) methylcellosolve and 0.25volume percent (0.122 gallon) water for 25 minutes at room temperaturethrough the dry cleaning wheel. As it is recirculated, the rinsecomposition withdrawn from the wheel was passed through a cartridge offinely divided clay impregnated with two weight percent palladium. Thiscatalyzed decomposition of hydrogen peroxide so that rinse solventreturned to the wheel was depleted of hydrogen peroxide. As a result,the residual hydrogen peroxide in the fabric was substantially removed.

Then the wheel contents were rinsed and extracted of liquid in threeminutes, following which hot air drying was conducted for seven minutes.

These results were obtained:

TAB LE Percent Blue Green Fabric reflectance reflectance whitenessSecured cotton:

efore 1 66. 5 74. 2 43. 4 After 82. 3 87. 4 67. 0

1 As placed in wheel.

EXAMPLE 13 TABLE 11 Percent Blue Green Guam reflec refiec- WhitefluidityFabric tance tance ness (rhes) scoured cotton:

1 Use of fabric once treated.

In practice, cleaning solvent extracted from the dry cleaning wheel andthe cleaning step of the process is collected in an appropriate storagecontainer. So too,.the

rinse solution. Prior to further use with a fresh change of soiledgarments, the solution is replenished with the additional aqueousbleaching material such as hydrogen peroxide.

Special techniques are useful when the aqueous componentof the cleansingcompositions is other than hydrogen peroxide. For example, with aqueoussodium hypochlorite or the like, it is especially beneficial to combinethe use of sodium hypochlorite with hydrogen peroxide. Thus, in onecontemplated procedure, the goods are initially treated with an organiccleansing solution in which the aqueous bleach phase is aqueous sodiumhypochlorite for a short period of time, say 3 to 15 minutes. Then,hydrogen peroxide is added and a further cleansing action is effected.This sequence of aqueous bleaching agents provides a unique.combinationof the particularly effective qualities of each. In addition, byutilizing the hydrogen peroxide step last, only hydrogen peroxide isleft in the fabric. It can be removed by treatment with the alcoholcontaining solvent rinse solution.

Techniques herein described are especially applicable to the cleansingof fabrics (or garments of fabrics) which possess both oleophilic andhydrophilic characteristics and hence are soiled (or stained) by botholeophilic and hydrophilic soils. In general, such garments areprimarily cotton-polyester blends. The so-called white goods of suchfabrics are advantageously treated. Colored fabrics whose dyes are setby oxidizing reaction also are treated with facility, the oxidizingaction of the aqueous bleach revitalizing the dye color. Of course,those dyes which are detrimentally effected by aqueous bleach materialsare less readily susceptible of this treatment. Nevertheless, becauseexposure to the aquous proxide phase is controlled, it is possible totreat colored fabric quite often without intolerable color degradation.

Temperatures of treatment in each of the steps herein discussed arethose normally encountered in cleaning operations. Ergo the prcoess canbe effectively used without recourse to unsual conditions of pressure ortemperature.

While the present invention has been described With respect to certaindetails of special embodiments, it is not intended that the invention beconstrued as limited thereto except and insofar as details are set forthin the claims.

We claim:

1. A method of treating fabric which comprises contacting the fabricwith a cleaning bath having as its principal components a continuousphase of substantially water immiscible organic cleaning solvent whichconstitutes a major portion of the bath and having dispersed therein andconstituting a minor portion of the bath, a discontinuous distinctaqueous bleaching phase substantially immiscible in the organic cleaningsolvent of a water soluble bleaching agent which bleaching agent issubstantially insoluble in the water immiscible organic cleaning solventof the continuous phase, terminating contact between the fabric andcleaning bath before serious fabric degradation due to the bleachingagent occurs and removing residual bleaching agent remaining in thefabric by rinsing the fabric with a substantially water immiscibleorganic cleaning solvent having a minor amount of a 2 to 5 carbonmonohydric alkanol.

2. The method of claim 1 wherein the solvent is a l to 3 carbonhalogenated hydrocarbon and the bleaching agent in the bleaching phaseis selected from the group consisting of hydrogen peroxide, alkali metalperoxides, hypochlorous acid and alkali metal hypochlorites.

3. A method of treating fabric which comprises contacting the fabricWith a two phase cleaning bath having an organic suspending agent and asits principal components a continuous phase of substantially waterimmiscible organic 1 to 3 carbon chlorinated hydrocarbon cleaningsolvent constituting a major portion of the bath having dispersedtherein and constituting a minor portion of the bath a distinctdiscontinuous aqueous bleaching phase substantially immiscible in theorganic cleaning solvent of a water soluble bleaching agent selectedfrom the group consisting of hydrogen peroxide, alkali metal peroxides,hypochlorous acid and alkali metal hypochlorites, terminating contactbetween fabric and cleaning bath before serious fabric degradation dueto the bleaching agent occurs and removing residual bleaching agentremaining in the fabric from said treatment by rinsing the fabric with asingle liquid phase rinse of the same organic cleaning solvent used incleaning having a minor concentration of a 2 to carbon monohydricalkanol.

4. A method of treating fabric with both oleophilic and hydrophiliccharacteristics which comprises contacting the fabric with a two phasecleaning composition having as principal components a continuous phaseof substantially water immiscible organic halogenated hydrocarboncleaning solvent throughout which is dispersed a distinct aqueousorganic immiscible phase of a water soluble bleaching agent, whichbleaching agent is substantially insoluble in the organic halogenatedhydrocarbon cleaning solvent of the continuous phase, said disperseddistinct aqueous phase constituting from 0.1 to percent by weight of thecleaning solvent in the continuous phase, separating the fabric fromcontact with the composition before significant fabric degradationoccurs and promptly removing residual bleaching agent in the fabric byrinsing the fabric with organic substantially water immiscible cleaningsolvent which has a minor portion of a 2 to 5 carbon monohydric alkanol.

5. The method of claim 4 wherein the cleaning composition also has along chain alkyl sodium phosphate, the solvent is selected from thegroup consisting of methylchloroform, perchloroethylene andtrichloroethylene and the bleaching agent is selected from the groupconsisting of hydrogen peroxide, alkali metal peroxides, hypochlorousacid and alkali metal hypochlorites.

6. The method of claim 4 wherein residual water soluble bleaching agentremaining in the fabric after separation from the cleaning compositionis removed by rinsing the fabric with a liquid rinse of the organiccleaning solvent having from 1 to percent by volume of said organiccleaning solvent of a 2 to 5 carbon monohydric alkanol.

7. The method of claim 6 wherein the rinse composition also has a smallamount of a water soluble, lower alkyl monoether of a glycol soluble inthe organic solvent of the rinse composition.

8. A method of removing residual water soluble bleaching agent from afabric containing residual bleaching agent from a cleansing treatment inwhich the fabric has been contacted with the water soluble bleachingagent which comprises rinsing the fabric with a rinse composi tion of asubstantially water insoluble organic cleaning solvent containingdissolved therein a minor concentration of a 2 to 5 carbon monohydricalkanol.

9. The method of claim 8 wherein the bleaching agent removed from thefabric during the rinsing and present in the rinsing solution isdestroyed by contacting the solution with an inorganic decompositioncatalyst for destroying the bleaching agent and thereafter contactingthe fabricrfurtherflwith the rinse composition which has had bleachingagents present so decomposed.

10. The method of claim 8 wherein the alkanol concentration in the rinsecomposition is from 1 to 15 percent by volume of the organic cleaningsolvent, and the rinse composition includes a water soluble lower alkylether of a glycol which is also soluble in the organic cleaning solvent.

11. The method of claim 8 wherein the rinse composition is a singleliquid phase and contains water in a concentration from 0.1 to 10 weightpercent of the organc solvent.

References Cited UNITED STATES PATENTS 1,966,915 7/1934 Baier 252-1042,749,313 6/1956 Williams et al 252-104 2,886,532 5/1959 Hale et a1.8111 X 2,914,374 11/1959 Harris et a1 8--111 3,355,385 11/1967 Macklet20210 X OTHER REFERENCES McCutcheons-Detergents and Emulsifier, 1967, p.255.

MAYER WEINBLATI, Primary Examiner US. Cl. X.R.

8-lll, 139, 142; 252-321

